The present invention relates to a window glass unit comprising a number of glass panes, preferably two or three held in spaced relation by a frame spacer elements and sealed to define at least one interpane space. The space or spaces contain a gas mixture with a high thermal insulating property.
Such window units are previously know for example from U.S. Pat. No. 4,019,295, Derner et al. In most such units manufactured the gas contained in the space or spaces is air. It has however been disclosed that other gases, inert gases and for example sulphur hexafluorid will give better insulating properties than air with respect to tranfer of heat and sound.
The gas mixtures previously proposed in this context seem to have been a result of experimental work. The gas mixture is composed of such gases which are known as having good insulating properties against transfer of sound or heat and they are mixed together to find a suitable compromise between a good sound and heat insulation. A way to find theoretical means to compose an optimal gas mixture for a certain application and certain desired insulating properties has not been presented in the literature.